As a camera module has been developed increasingly, the camera module has been mounted on various equipments such as a digital camera, a note book computer, PMP, MP3, etc.
In particular, the camera module is mounted on most of mobile communication terminals such as cellular phones and is appeared in a market and used increasingly.
FIG. 1 is an exploded and perspective view of a conventional small camera, and FIG. 2 is a sectional view showing a driving unit shown in FIG. 1 before it is driven and FIG. 3 is a sectional view showing the driving unit shown in FIG. 1 after it is driven.
As shown in FIGS. 1 to 3, a conventional small camera includes a lens group 50 comprising a plurality of lens for adjusting an amplification of a subject to be pictured, a lens holder 55 for mounting the lens group 50 and driving in an optical axial direction, a fixing unit 60, a plate spring 65 to be supported to the fixing unit 60 for guiding the lens holder 55 to be moved in an optical axial direction, a magnet 70 fixed to the fixing unit 60, a wound coil 72 fixed to the lens holder 55 in such a way to be exposed to a magnetic filed of the magnet 70 and further for producing a force to move the lens holder 55 in an optical axial direction by receiving a magnetic flux when a electric current is applied thereto, a magnetic body 74 fixed to the lens holder 55 and further for moving the lens holder 55 with an attractive force to the magnet 70 and fixing it to a predetermined location, an image sensor 80 for picturing an image of a subject to be pictured passed through the lens group 50, and a control unit for controlling the wound image 72 and the image sensor 80.
Here, the plate springs 65 are mounted to the upper and lower part of the lens holder 55, respectively, and acts to guide the lens holder 55 to be moved precisely in an optical axial direction when the lens holder 55 is driven up and down by the wound coil and the magnet 70 as shown in FIG. 3.
Additionally, the plate spring 65 acts to return the lens holder 55 to its initial location as shown in FIG. 2 with an elastic recovery force when the lens holder 55 is moved upward or downward as shown in FIG. 3.
Meanwhile, the plate spring 65 keeps a horizontal state as shown in FIG. 2 when it is vibrated continuously up and down through an inertia force moving the lens holder 55 up and down and then a predetermined time period is passed.
Accordingly, there arises a problem in that it takes much time for the lens group 50 mounted to the lens holder 55 to decide a focus of a subject to be pictured.
In addition, there arises another problem in that the plate spring 65 is made with typically iron material and thus when the plate spring 65 is moved excessively up and down, a deformation to the plate spring 65 is occurred or a noise caused from a contact of the upper surface or lower surface of the plate spring 65 with other components is occurred.